The present invention relates to inflatable buoys, and more particularly to buoys that can be dropped into a body of water, submerged and inflated below the surface of the water.
Inflatable buoys of the type just described are normally dropped from air for disposition in the water at remote or inaccessible locations. The buoys normally include an inflatable bag, an instrument package, and an anchor that prevents the buoy from drifting with the current. A variety of inflation methods are utilized to inflate the bag, including induction systems in which the bag is inflated during descent from the airplane as well as pressurized gas and propellant charges.
A preferred inflation method is to utilize a propellant charge. However, the burning temperatures of propellants are quite high and can possibly injure a heat sensitive, inflatable bag. As a consequence, means for cooling the propellant have been devised. These means include injecting the propellant into a chamber containing carbon dioxide, pressurizing the carbon dioxide, and when the carbon dioxide reaches predetermined pressure, injecting the carbon dioxide into an inflatable bag. While this system works very satisfactorily, it is desirable to eliminate the extra bulk, weight and expense of a carbon dioxide cooling system, while using conventional gas generating propellants. Other cooling means, such as sensible heat sinks comprised of screens, steel shavings, steel dust, aluminum oxide or magnesium oxide granules consume a significant storage space. Also, passive-type cooling means such as water cooled heat exchangers are bulky and complex.